1. Field of the Invention
This invention relates to a two stage process for the production of oxygen and hydrogen from water using electrolysis with added iodine in the first stage to produce hydrogen iodide which is thermally decomposed in the second stage without electrolysis.
2. Description of the Prior Art
The prior art discloses a three stage process for the production of hydrogen by the electrolysis of water by producing intermediate methyl iodide. A cyclic process for obtaining oxygen and hydrogen is disclosed in the "Proceedings of the 4th World Hydrogen Energy Conference", California, USA, June 13-17, 1982, vol. 2, pages 579 et seg., the process being such that oxygen is produced electrolytically in the anode space and methyl iodide is produced in the cathode space. Then the methyl iodide is thermally decomposed with the addition of water and iodine to produce methane, methanol and iodine. The methane can be further decomposed in a steam reformer to produce carbon monoxide and hydrogen. However, the requirement of three stages is an unattractive feature of this prior art process.
The decomposition of HI.sub.x to hydrogen and iodine is known. This decomposition, for example, constitutes a step in the "sulfur-iodine" process of General Atomic (D. O'Keefe et al. "Preliminary results from Bench-Scale Testing of a Sulfur-Iodine Thermochemical Water-splitting Cycle", Int. Journal of Hydrogen Energy, vol. 7, No. 5, pages 381 et seq.). In this process, the HI.sub.x is freed of iodine, dried and conveyed to a decomposer in which the decomposition of hydrogen iodide into hydrogen and iodine takes place.